Thanks Kim. This spider was alone in the middle of an elaborately constructed tent web strung between branches of an Acacia dealbata. You can see its fuzzy shape just to the right of centre in image 3. It was much larger than the numerous uloborid spiders I see around the garden (Uloboridae sp. (family) (Unidentified venomless spider) on 5 Nov 2017) that have very untidy webs. I thought this was a tent web spider.